it would be great and very usefull to be able to have several uv coordinates per vertex in order to have:_ 1 uv coord for the diffuse texture_ 1 uv coord for bumpmap texture _ 1 uv coord for speculare_ ...

So long as it was not actually necessary to set the coordinate for each separate level every time. The default should still be coincident UV coords, able to be separated as a choice. But yeah, great idea.